O2/CO2气氛下稻秆添加磷酸二氢铵对固钾及灰熔融特性的研究

研究了21%O₂/79%CO₂气氛下,磷酸二氢铵对稻秆不同温度下的固钾能力及对灰熔融性的影响。利用电感耦合等离子体发射光谱(ICP-AES)、X射线衍射(XRD)以及扫描电子显微镜(SEM)等检测手段,对稻秆燃烧灰中K元素含量、产物物相以及微观形貌进行分析。固定床燃烧固钾实验表明,添加NH₄H₂PO₄能够有效提高稻秆固钾率,900℃下稻秆自身固钾率为14.65%,添加NH₄H₂PO₄后固钾率为68.79%,可以有效抑制生物质燃烧过程中碱金属以气态形式析出,并缓解了灰结渣现象。700℃燃烧条件下NH₄H₂PO₄和钾反应的主要产物为KPO₃;900℃下反应的主要产物为高熔点物质K₂CaP₂O₇,从微观形貌可以看出NH₄H₂PO₄能够抑制灰颗粒的烧结,添加NH₄H₂PO₄能有效提升稻秆灰熔点。

Influence of ammonium dihydrogen phosphates additive on potassium fixation capacity and ash fusibility for rice straw combustion in an O2/CO2 atmosphere

Particle agglomeration, fouling on the heating surface and other issues are closely related to the alkali metals during biomass thermo-chemical conversion. The potassium fixation ability and ash fusing characteristics in the combustion of rice straw (RS) added with ammonium dihydrogen phosphate (NH₄H₂PO₄) were studied in a 21%O₂/79%CO₂ atmosphere. The reaction residue from the experiment in a drop tube furnace was analyzed with inductively coupled plasma atomic emission spectrometer (ICP-AES), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The potassium retention ratio of co-combustion of RS and NH₄H₂PO₄ is higher than that of RS alone, especially at 900℃, and the retention ratio increases from 14.65% to 68.79%. The reaction between NH₄H₂PO₄ and alkali metals in rice straw leads to the formation of KPO₃ at 700 ℃ and K₂CaP₂O₇ at 900℃, which is a high melting point compound. SEM analysis on residue indicates the agglomeration is inhibited, and the ash fusion temperature of RS is increased by adding NH₄H₂PO₄. These results can be helpful to the research and development of high-alkali biomass clean utilization process.